280,521 research outputs found
Uncertainty in Soft Temporal Constraint Problems:A General Framework and Controllability Algorithms forThe Fuzzy Case
In real-life temporal scenarios, uncertainty and preferences are often
essential and coexisting aspects. We present a formalism where quantitative
temporal constraints with both preferences and uncertainty can be defined. We
show how three classical notions of controllability (that is, strong, weak, and
dynamic), which have been developed for uncertain temporal problems, can be
generalized to handle preferences as well. After defining this general
framework, we focus on problems where preferences follow the fuzzy approach,
and with properties that assure tractability. For such problems, we propose
algorithms to check the presence of the controllability properties. In
particular, we show that in such a setting dealing simultaneously with
preferences and uncertainty does not increase the complexity of controllability
testing. We also develop a dynamic execution algorithm, of polynomial
complexity, that produces temporal plans under uncertainty that are optimal
with respect to fuzzy preferences
Algorithms for Analysing the Temporal Structure of Discourse
We describe a method for analysing the temporal structure of a discourse
which takes into account the effects of tense, aspect, temporal adverbials and
rhetorical structure and which minimises unnecessary ambiguity in the temporal
structure. It is part of a discourse grammar implemented in Carpenter's ALE
formalism. The method for building up the temporal structure of the discourse
combines constraints and preferences: we use constraints to reduce the number
of possible structures, exploiting the HPSG type hierarchy and unification for
this purpose; and we apply preferences to choose between the remaining options
using a temporal centering mechanism. We end by recommending that an
underspecified representation of the structure using these techniques be used
to avoid generating the temporal/rhetorical structure until higher-level
information can be used to disambiguate.Comment: EACL '95, 8 pages, 1 eps picture, tar-ed, compressed, uuencoded, uses
eaclap.sty, a4wide.sty, epsf.te
Bipolar querying of valid-time intervals subject to uncertainty
Databases model parts of reality by containing data representing properties of real-world objects or concepts. Often, some of these properties are time-related. Thus, databases often contain data representing time-related information. However, as they may be produced by humans, such data or information may contain imperfections like uncertainties. An important purpose of databases is to allow their data to be queried, to allow access to the information these data represent. Users may do this using queries, in which they describe their preferences concerning the data they are (not) interested in. Because users may have both positive and negative such preferences, they may want to query databases in a bipolar way. Such preferences may also have a temporal nature, but, traditionally, temporal query conditions are handled specifically. In this paper, a novel technique is presented to query a valid-time relation containing uncertain valid-time data in a bipolar way, which allows the query to have a single bipolar temporal query condition
Temporal stability and psychological foundations of cooperation preferences
A core element of economic theory is the assumption of stable preferences. We test this assumption in public goods games by repeatedly eliciting cooperation preferences in a fixed subject pool over a period of five months. We find that cooperation preferences are very stable at the aggregate level, but less so at the individual level. Nevertheless, individual preferences are sufficiently stable to predict future behavior fairly accurately. Our results also provide evidence on the psychological foundations of cooperation preferences. The personality dimension 'Agreeableness' is closely related to both the type and the stability of cooperation preferences.Social preferences, preference stability, conditional cooperation, free riding, personality, Big-Five.
Inter-temporal discounting and uniform impatience
The uniform impatience hypothesis, a joint requirement on endowments and preferences, was imposed in the literature to prove equilibrium existence in infinite horizon sequential economies. In this note, we characterize this assumption in terms of asymptotic properties on inter-temporal discount factors.Uniform impatience, inter-temporal discounting. JEL Codes: D50, D52.
Managing temporal relations in the MAESTRO scheduling system
A set of viewgraphs on managing temporal relations in the MAESTRO scheduling system are given. The viewgraphs present information on such topics as why scheduling is hard, managing temporal relations, constraints on the placement of a single activity, constraints between activities, soft constraints (such as preferences), and contingency handling
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